This was Easter morning. Broke down in front of Buck Hill. Trailered it back to Bruce's.
Took it apart and the front piston was cracked. The rings were totally cracked and loose too.
No worries, parts are on the way.
Also found the source of all that exhaust smoke...
When I looked in the rear cylinder the wall was scored up in a deep U-shape. Turns out one of the wrist pin circlips had come loose and so the wrist pin was rubbing against the side wall. Prolly have to go with a new jug for that since it's already bored 20 over.